#include<bits/stdc++.h>
using namespace std;
int main()
{
	char ch;
	cin>>ch;
	if('a' <= ch && ch <= 'z')
	{
		if(ch == 'a')
			cout<<"z";
		else
			cout<<(char)(ch-1);
	}
	else
		cout<<ch;
    return 0;
}

